Perforating apparatus having a stripping medium mounted within a chamber in the punch member



April 3. 1956 P. H. TAYLOR PERFORATING APPARATUS HAVING A STRIPPINGMEDIUM MOUNTED WITHIN A CHAMBER IN THE PUNCH MEMBER Filed Jan. 8, 1953 2Sheets-Shem l INVENTOR.

Rani 22 207 P. H. TAYLOR April 3, 1956 2,740,475 PERFORATING APPARATUSHAVING A STRIPPING MEDIUM MOUNTED WITHIN A CHAMBER IN THE PUNCH MEMBERFiled Jan. s, 1953 2 Sheexs-Sheei 2 A b a v 4/ M- INVENTOR. am. 22 20? BBY plements PERFQRATING APPARATUS HAVING A STRIP- PING MEDIUM MOUNTEDWITHIN A CHAMBER IN THE PUNCH MER RER Paul H. Taylor, Grand Island, N.Y., assignor to Wales- Strippit Corporation, North Tonawauda, N. Y., acorporation of New York Application January 8, 1953, Serial No. 330,19729 Claims. (Cl. 164-110) The present invention relates to perforatingimplements, and more particularly to self-contained perforating imsuchas may be used singly or in multiples in a conventional punch press forpunching holes in sheet metal and similar materials.

Self-contained perforating unit have been universally adopted byindustry for use especially Where it is desired to punch a number ofholes simultaneously in sheet metal or similar materials. The individualperforating devices are either secured to a template, or mountedadjustably on bed rails in a press, so that they can be placed in apattern corresponding to the pattern of holes which it is desired topunch in a work piece, and so that they can be actuated simultaneouslyby the press ram on the downward, working stroke of the ram to punch thedesired holes in the work piece. Devices of this type have the advantagethat each unit contains both a punch and die, and that these are mountedin alignment. In addition, in this type of perforating apparatus theworkstripping means also forms part of the perforating unit. Hence, ifanything goes wrong with a unit, it can be removed as a unit andreplaced as a unit. Thus, the downtime of presses, in which thesedevices are used, is reduced to a minimum. Furthermore, theseperforating implements are adaptable to either long or short productionruns, which is also a major advantage.

Self-contained perforating units have been made in a number of differentforms. In a perforating device such as disclosed in the Wales U. S.Patent No. 1,955,866, granted April 24, 1934, and assigned to theassignee of the present application, the downward working stroke of thepress ram stores energy in a wound steel wire spring, which forms partof the perforating unit; and this spring operates to withdraw the punchfrom the Work after the perforating stroke is completed. The Work, whichthese perforating implements can do, is limited, however, by thecapacity of the steel spring used for stripping. To punch maximumthicknesses of stock material a heavy steel stripping spring has to beused. Such a spring increases the overall width of the perforating unitwhich in turn limits the closeness perforating units can be positionedto one another, thereby limiting the closeness at which adjacent holescan be punched in a single perforating operation. As a result thestripping units of perforating implements such as disclosed in the Walespatent mentioned are frequently overloaded with the result that earlyfailure occurs. It is also necessary with perforating Llni'tS such asdisclosed in the Wales patent mentioned to sharpen the punch frequently,or to assist sticking punches to strip by striking the work with amallet, because the nature of the loads on the stripping spring made itimpossible to strip a dull punch from a workpiece.

Another disadvantage of the underforce spring in the existingperforating unit is that in large setups, where from four hundred to onethousand perforating implements are employed, sometimes one punch willstick and release upon withdrawal of the ram, and the punch will springout of its holder and lay crosswise over the worktates Patent ency tobond is less.

2,740,475 Patented Apr. 3, 1956 2 piece, press bed or perforating unit.The operator, not seeing this, brings the ram down for the nextoperation and this often results in spoiled work, damaged perforatingholders, and in some instances a damaged press. At times, also, thi willresult in an operator making an entire production run withoutdiscovering that one hole is not being punched in the work. In manyinstances this has resulted in the necessity for drilling that hole inthe entire production run from a fixture by locating from.

a previously punched hole.

Another limitation on perforatingunits, such as shown in the Walespatent mentioned, has been the necessity of limiting the material to bepunched to one-eighth inch thickness if a standard punch press was to beused, since, where work of more than one-eighth inch thickness was to bepunched, stripping requirements demanded springs of such size that asingle stripping spring would be impractical for standard pressshut-heights. Therefore, special types of punch presses had to bedesigned, where it was desired to punch material of more than one-eighthinch thickness on given hole centers with a perforating implement suchas disclosed in the Wales patent above mentioned. With such machinesithas been possible, using perforating implements such as shown in theWales patent mentioned, to punch sheet metal of one-quarter inchthickness with the desired closeness of the hole centers. Such machines,however, are expensive.

The closeness of the hole center and the thickness of the material whichcould be punched was, therefore, ordinarily governed by the beststripping spring punch compromise which could be made between the holderwidth and the necessary stripping force. This means that for many jobstwo or three operations were necessary to punch holes on given centersin a material of a given thickness. i

To overcome this difiiculty, perforating units were developed, such asdisclosed in Wales U. S. Patent No. 2,326,588, granted August 10, 1943,in which a series of springs are arranged in tandem above the holder.However, this arrangement of spring mechanism makes the punch elementextremely fragile, andthin, and subject to considerable bending becauseof its long columnar nature. These units, furthermore, are of greaterheight than can be used in a press having a standard shut height, whichmeans that their use has been confined to large expensive presses withgreater open height. In addition, such units are costly because theyrequire accurate and delicate assembly. Long punches such as have beendescribed above also create ditficulty in manufacture because the bodysection must be tough while the perforating end must be glass hard toresist abrasion from the wearing of the material as the punch is forcedtherethrough. This has always presented a problem in heat treatment asthe punches must first be heated to the proper temperature, quenched inoil, water, or air, as the material requires, and then the body behindthe punch tip must be drawn back to a tough condition while theperforating end is maintained tothe proper hardness for perforating.This offers a chance for two errors in production which are costly andditficult to avoid. In the first instance, punch steels by nature arenot generally adapted to be tough butare rather adapted to be hard toresist abrasion; and the drawing back of one section to a toughcondition is extremely difiicult, hazardous and must do the perforating,gets soft; and it will not function properly. If the transition betweenthe heat treatedand drawn section occurs at the reduced section of thepunch where it meets the tip, failure of the punch tip will most surelyresult,since the molecularfstr'ucture of the material through thissection is diflerent and its tend- Here again a compromise is generpunchtip fails the entire punch assembly must be dis pensed with, which is acostly replacement item.

To overcome the deficiencies of the self-contained perforating unitsusing mechanical springs as the stripping means, perforating units weredevised utilizing compressible liquids to efi'ect stripping. Units ofthis type are disclosed in my pending U. S. patent applications SerialNos. 185,604, now Patent No. 2,732,898, and 185,606, filed September 19,1950. With these perforating units it is possible to achieve greaterstripping forces, and hence to perforate material up to three-quarterinch thickness on the same hole centers as could be punched with theprior perforating units, using mechanical springs, which were limited topunching sheet metal of a thickness of one-quarter inch. In addition,the perforating units of these applications can be mounted within theshut height of standard presses. Obviously, these devices are much moreefficient since narrower holder widths and smaller shut heights arepermitted. These units are much more suited to closer center applicationand to punching heavier stock in smaller presses. Perforating units,such as disclosed in applications above mentioned, however, are morecostly than the individual perforating units employing mechanicalsprings as the stripping means. Hence, the perforating units, usingliquid springs, such as shown in my applications above mentioned, areordinarily used only for perforating heavy duty materials such as thosebetween one-quarter inch and three-quarter inch thickness.

One object of the present invention is to provide a perforating unitwhich can be manufactured at a cost less than the cost of theperforating units using liquid as the stripping medium, and yet whichcan perforate metal sheet of a thickness such as can be punched with theliquid spring units, and which can be used within the shut height ofstandard punch presses.

Another object of the invention is to provide a perforating unit of thecharacter described which will continue in satisfactory operation for alonger period than selfcontained perforating units as heretofore made,and which is reliable, and which will have a stripping spring pressureeven in excess of that required.

Another obiect of the invention is to provide a selfcontainedperforating unit which may be used with either punch presses of normalshut heights or with punch presses of special design having larger shutheights, thereby reducing the inventory of punch units required andproviding a single unit which will serve two purposes and which is moreor less universal in its adaptability.

Another object of the invention is to provide a perforating unit whichcan be made of smaller width than units of prior design, and still punchand strip materials of greater thickness.

Another object of the invention is to provide a selfcontainedperforating unit in which the stripping forces are more than adequatefor the job, and which neednot, therefore, be overloaded, as has beenthe practice with mechanical spring units heretofore.

Another object of the invention is to provide a selfcontainedperforating unit which has stripping forces more than adequate for thejob with the result that the punchdoes not need to be sharpened asfrequently as heretofore and with'the further result that mallets orother types of percussion implements do not have to be used to assist instripping the work from the punches when stuck.

A further object of the invention is to provide a selfcontainedperforating unit which will have a life many times that of perforatingunits employing mechanical springs.

Another object of the invention is to provide a per forating unit of thecharacter described in which the load-- carrying capacity of thestripping means can quickly be brought up to normal should loss of loadoccur for any reason. When a steel spring loses load, this is due almostalways to failure of the spring itself, and no adjustment can be made byspacers or otherwise to restore the load-carrying capacity of thespring.

Another object of the invention is to provide a selfcontainedperforating unit in which the resilient stripping means is adjustable asto force while maintaining the same stroke and overall travel of thepunch.

Another object of the invention is to provide a perforating unit inwhich the life of the punch will be considerably greater than the punchlife of conventional perforating units.

Another object of the invention is to provide a perforating unit whichhas increased strength and much less side deflection under load thanconventional perforating units. Most punch failures occur at the momentthat stripping begins because the punch has been deflected in thepunching operation, and because this deflection is suddenly releasedwith a snap as the press ram is withdrawn. This deflection causesexcessive punch breakage.

Another object of the present invention is to provide a perforating unitin which the punch-supporting member has greater rigidity than theconventional units.

Another object of the invention is to provide a selfperforatingimplement in which the member that supports the punch may be guideddirectly in a holder without stripping means being interposed betweenthat mem. her and the holder.

A further object of the invention is to provide a perforating unithaving an inserted type punch, which will reduce punch costs.

Another object of the invention is to provide a perforating unit inwhich the insert type punch is joined to the main body of the punch atthe point where convert tional punches generally fail so that much lesspunch failure will result since the punch is already split from the mainbody at the transition point where stress concentration occurs.

A further object of the invention is to provide a selfcontainedperforating unit in which the perforating implement is a smallreplaceable insert, which is mounted within a tough shock-resistantstructural member adapted to transmit the force of the press theretowhile containing the resilient stripping means.

Another object of the invention is to provide a composite punch in whichthe punch body is made of an alloy capable of being drawn in heattreatment to a maximum of toughness, and the punch tip is separate fromthe punch body and can be made of any suitable alloy for maximumhardness, both parts being adapted thereby to mass production inseparate controlled production processes. In prior solid punches, acompromise between a good punching alloy and a good punch support alloymust be made, because the tip and body of the punch are integral withone another and the punch must be subjected to a separate drawingoperation after heat a treatment in an effort to impart toughness to thebody of the punch while maintaining hardness at its tip, withoutadequate assurance that either quality is achieved.

Another object of the invention is to provide a perforating implement inwhich the-stripping medium strengthens the punch.

Another object of the invention is to provide a perforating implement inwhich the stripping medium is mounted in a chamber ina structural memberof little structural strength rather than on the periphery of thatmember,

thereby to provide a stable structural member for transmission of theperforating force .to the punch.

Another object of the invention is to provide a perforating implementusing a compressible solid as the stripping element and in which thesolid is mounted within a chamber provided in a tubular member thatcarries the punch.

Another object of the invention is to reduce the mass of the punch andstripping spring assemblage so that the natural frequency which can beattained is much higher than that of a conventional punch with theresult that the punch and stripping spring assemblage can bereciprocated at higher speeds.

A further object of the invention is to provide a stripping medium ofreduced weight .and volume so that its mass is substantially less thanthat of stripping means used in conventional punches with the resultthat the cycling frequency can be higher than with a conventional punchand stripping spring.

Another object of this invention is to provide a punch comprising astructural punch column which may be made from standard steel tubing anda short economical screwmachine-manufactured plug or punch insert bit,in place of a long solid bar of costly tool steels as required inpresent punches for use in self contained perforating implements.

Another object of the invention is to provide a combined perforatingpunch and stripping member of reduced mass, so that if the punch wouldstick in the workpiece and then break free after the withdrawal of thepunch ram, the generated force from said mass accelerated by said springmedium will apply less force to the restraining means on saidperforating assemblage or to the press ram, whichever it may engagefirst than .is the case with conventional perforating units, wherebydamage is minimized.

Still another object of the invention is .to provide a selfcontainedperforating implement so constructed that none of the forces ofstripping the work from the punch are transmitted through the holder.

A still further object of the invention is to provide a self-containedperforating implement in which means is provided for preventing theperforating assemblage from jumping out of the holder in event the punchsticks in the work during a perforating operation.

Still another object of this invention is to provide a self-containedperforating implement employing quick disconnect anti-jump means so thatthe punch may be rapidly removed for sharpening.

Other objects of the invention will be apparent hereinafter from thespecification and from the recital of the appended claims.

In the drawings:

Fig. 1 is a side elevation of a self-contained perforating unitconstructed according to one embodiment of this invention;

Fig. 2 is a section through this unit taken on the line 2-2 of Fig. 1and looking in the direction of the arrows;

Fig. 3 is a section similar to Fig. 2 but showing the moving parts ofthe unit at the end of the working stroke of the punch;

Fig. 4 is a section on the line 44 of Fig. 2, looking in the directionof the arrows;

Fig. 5 is a fragmentary side elevation, partly broken away, showing theupper part of a punch holder made according to a modification of theinvention and having means for adjusting the stripping preload;

Fig. 6 is a side elevation, similar to Fig. 1, illustrating a furtherembodiment of this invention;

Fig. 7 is a fragmentary vertical section through this unit on anenlarged scale;

Fig. 8 is a section, similar to Fig. 7, but showing the moving parts ofthe unit at the end of the working stroke;

Fig. 9 is a fragmentary section taken on the line 99 of Fig. 7, lookingin the direction of the arrows;

Fig. 10 is a section on the line 10-10.of Fig. 8, look ing in thedirection of the arrows; and

Fig. 11 is a detail View showing in rear elevation the structure of the.novel stripping means of the perforating unit of Figs. 6 to 10inclusive.

Referring first to the embodiment of the invention shown in Figs. 1 to 4inclusive, denotes the perforating implement generally. This implementcomprises a C-frame 21 having upper and lower arms 22 and 23, and

having a pilot pin 24 projecting downwardly from itsbase, whereby theperforating implement may be located in a precision-located pilot holein a template base 25 of the press upon which the perforating implementis being used. Mounted on the lower arm 23 of the frame is a die member27. This die member may be of conventional construction, having a dieopening 28 (Fig. 2) therein and being relieved below said die opening,as indicated at 29, to provide a discharge passage or chute to theoutside through which the slugs punched from the work are discharged.

Mounted in the upper arm 22 of the frameis the punch assembly 30. Thisis mounted in axial alignment with the die member. This assemblycomprises a cylindrical, tubular member 31 that is closed at its upperend and that has a punch bit 33 mounted in its lower end. The tubularmember 31 has a conical bore portion 34 at its lower end and the punchbit 33 has a correspondingly tapered conical portion 35 which fits witha press-fit tightly into this conical portion 34 of the tubular member.

Reciprocably mounted in the tubular member 31 above the punch bit 33 isa piston 37. This piston bears at its lower end on a pin or crossbar 38which passes through diametrically opposed slots 39 in the tubularmember 31 and engages at its opposite ends in apertures in a tubularstripping collar 40.

The tubular punch member 31 holds .a cylindrical, compressible solidmember 46 made of a solid plastic material of high compressibility, suchas a hard silicone, nylon, polystyrene, etc. The columnar member 46hottoms at its upper end in the tubular member 31 and engages at itslower end against a sealing member 48 that in turn engages against theupper end of the piston '37.

The punching force is transmitted from the ram (Fig. 3) through thetubular member 31 to the punch bit 33. During a working stroke, thestripping member 49 moves with the punch 33 and the tubular punch member31 until it strikes the sheet metal plate or other workpiece 56 (Fig. 3)which is to be perforated, being driven by tubular punch member 31,.compressible solid 46, seal 48, piston 37 and pin 33. On the furtherdownward stroke of the punch, effecting the perforating operation, thesolid member 4c is compressed and reduced in volume through action ofstripper collar 40, pin 33, piston 37 and seal 48, with the result that,when the ram 45 moves upwardly on its return stroke, releasing thepressure from the tubular member 31, the solid member 46 will expand toits former volume, forcing the tubular member 31 upwardly to withdraw,that is, to strip the punch 33 from the workpiece 50.

The stripping movement of the punch continues until the lower end 52 ofthe slot 39 in the tubular member 31 strikes or stops the pin 38. Thepunch assemblage 30 is then returned to its upper position shown in Fig.3 by a coil lifter spring 55 which surrounds the tubular member 31 andis fastened at one end 56 in the tubular member and rests at its otherend on the upper arm 22 of the frame 21.

In the punch assemblage 30, the punch member, instead of being a slenderperforating implement surrounded by a tubular stripper, comprises atubular member, which is cored out so that the core, or slender,lowstrength inner portion has been removed and replaced by acompressible solid member 46. This compressible solid member strengthensthe tube as well as serving as the stripping medium. The punchassemblage in the perforating unit illustrated in Figs. 1 to 4inclusive, then, comprises a closed tubular member 31 having thestrength and rigidity normally associated with cylindrical members ofthe same diameter andlength.

The punch bit 33 itself is made of a material adapted to homogeneousheat treatment so as to have efficient perforating pro erties and bestructurally strong and resist abrasion. The compressible solid member46 is highly efficient in operation; and the stripping member is lightweight. Therefore higher punch velocities can be obtained with theperforating punch assemblage of the present invention because of thereduced mass.

Fig. 3 shows positions of the parts upon completion of the perforatingoperation, the punch member 33 having perforated the workpiece 56,removing the slug 51 therefrom. and the stripping collar 40 has beenmoved upwardly with reference to the tubular member 3i. so that the pin38 has energized the piston 37 which in turn has compressed or reducedthe volume of the compressible solid member 46. Upon withdrawal of thepress ram,

stated above. stripping collar 4i acts against the workpiece St) towithdraw the punch element 33. after which, due to lifter spring 55, theapparatus again assumes a position such as shown in Fig. 2, theelevating or lifting spring 55 having lifted the assemblage enough topermit the removal or replacement of work thereunder.

The mating tapers 34 and 35 of the tubular member Ill and of the punchelement 33, respectively, are a lockin: taper. the punch element beinginitially forced tightly into the tubular member 31. On each succeedingoperation the punch element is driven still more tightly into thetubular member and it cannot become disengaged therefrom by the normalstripping load. The reason. for this is that the tapers, in addition tobeing locking, have a larger ratio of area to the load between the punchthan to the thickness of the material which is to be punched by theassemblage. which guarantees that the surface friction between thetapers is greater than the friction between the punch and the hole sothat the punch element will be securely held in the tubular member.However, by use of a. suitable tool, the punch element can be removedreadily from the tubular member for replacement when it becomes dull orshould it be broken.

The pin 38, which transmits the stripping loads, is preferably a tubularmember consisting of a rolled plate which, when embedded and forced intothe aligned aperturcs in collar 40. locks therein and by virtue of itselasticity seeks to regain its shape, thus holding it the more securelyin position. This member is shown in greater detail in the cross sectionof Fig. 4 which illustrates how the pin is lodged tightly in theexternal collar 4!) to be engaged by the piston 37. Obviously a.rectangular pin or any other suitable pin can be used in place of pin 33illustrated.

While the compressible solid member 46 is shown as a long cylindricalmember, it will be noted that, when the apparatus is at rest. the punchelement 33 is withdrawn up within the stripping collar 49 a slightamount (Fig. 2) so that no n initial operation of the device thestripping member 46 will be distorted initially or preloaded before theworkpiece is engaged. the solid member 46 being compressed on e ement ofstripper with the work. While this is satisfactory in most cases, it issometimes necessary to preload the stripping medium either by ini tialdistortion or compression before any travel takes place. To this end amodified form of tubular member may be employed, such as shown in Fig.5.Here a tubular member 3 1 is employed that is threaded internally at itsupper end to receive an adjusting screw 64) which bears amino nvlon seal61 which, in turn, bears against the compressible solid member 46. itwill be obvious that the member 60 can be threadedly adjusted in thetubular momlfl t 3 so as to orel ad the compressible solid member 46,while still maintaining the same'punch stroke. since the cylindricalmember 31' may be made of the 8 same length as the tubular member 31,both being of the same length with-respect to the shut height of theperforating unit. It will furthervbe obvious that member 1 can be madeof stainless steel tubing, cutting the cost of machinery.

A further modification of the invention is shown in Figs. 6 to 11inclusive. In order to obtain increased volume for perforation of athicker piece of material, the compressible member in this embodiment ofthe invention is a tapered member 76. The use of such a member permitsof increase in the volume of compressible material while maintaining thearea which engages the piston. The tapered member 76 tapers from itsupper end downwardly to its lower end and at its lower end is ofsubstantially the same diameter as the diameter of the cylindricalcompressible member 46 shown in the embodiment of Figs. 1 to 3inclusive. The tapered compressible member permits of longer strokeloads for a given volume and pistonforce. Because of the enlargedportion and tapered section of the compressible solid member with itsincreased volume the perforating unit illustrated here is capable ofperforating approximately twice the thickness or material as is theperforating unit shown in Figs. 1 to 5. This is because the increasedvolume of the compressible solid member permits a longer stroke with agreater force than is permissible with the device of Figs. 1 to 5. Aunit made according to this embodiment of the invention may be shorter,narrower and still develop much greater stripping force with longerspring life than conventional units with single steelwire springs.

In this embodiment of the invention the perforating unit comprises aC-frame 121 having an upper arm 122 and a lower arm 123. The lower armcarries a die 127 which may be of conventional construction. Mounted inthe upper arm 122 is a tubular member 71. This 'mernber has a conicalbore 72 which contains the correspondingly conically shaped compressiblesolid member 76. This compressible member is made, like member 45, of acompressible plastic, such as a hard silicone, or the like. The upperend of the tubular member 71 is sealed by a cap 73 which threadsadjustably onto the tubular member 71. interposed between the cap andthe solid member 76 are a variable series of washers 74 and a nylon seal77. The compressible solid 76 bears at its lower end against a nylonseal 73 which, in turn, seats against the upper end of a piston 77.

In this form of the invention the stripper member comprises a C-shapedmember 80 which seats on a proiection 81 formed on the lower end of thepiston '77. This projection engages in a hole 82 formed in the upper arm83 of the C-member 80. The upper arm 83 of the C-rnember extends througha slot 8 6 in the tubular mcrnber 71. Because of the increased loadingof the unit of Figs. 6 to 11, it is desirable that the tubular member 71be not cut or slotted in two places, since this tends to weaken thestructure through which the compressible or punching loads are carried.Accordingly, the tubular member 71 is slotted at one side only asindicated at 84, the Q-frame member 86, being inserted through the slot34 to fit over the protuberance 81 on the piston 77 so that it is lockedto the piston and cannot move relative thereto with respect to the axisof the punch.

The C-frame 89 is held in engagement with the piston 77 by a coil spring85 which is mounted within a hole 86 in the upper arm 122 of theperforating unit, and which engages at one end in a hole 37 in thestripper member and at its other end over a pin 83 that is secured inthe upper arm 122 of the C-frame. This spring operates to elevate thepunch as well as to hold the member 80 in engagement with the pistonmember 77. The C-frame can readily be removed by pulling it down oif theprotuberance 81 of the piston 77, and sliding it to the right in Fig. 7.

Because of the high loads which must be transmitted through thisG-member 80, I prefer to make it of general 9 I-beam type constructionin cross-section ,as is shown in detail in Figs. 10 and 11. In this waythe excessive high loads can be carried at :und the body member '71 forthe purposes described.

The punch d in this embodiment .of the invention is formed with acylindrical .surface 91 at its upper end, which is of somewhat largerdiameter than its operating portion and which has a press fit in thelower end of .the tubular member 71. The lower arm 93 of the stripper 80has a hole 94 through it which is axially aligned with the axis of thetubular member 71 and through which the punch 94) can move on itsworking and return strokes.

By varying the thickness or the number of washers 74 the compressiblesolid member 76 can be preloaded as desired.

It will be noted that the C-frame stripper 80 and its counterpartstripper 4%) of Fig. 2 are larger than the bore in the upper arm 22 or.122 of the perforating unit in which the tubular members .31 and 71,respectively, are mounted. This prevents the punching assemblies 30, or130, respectively, from jumping out of their respective holders. If thepunch jumps after failure to strip, which has occurred in prior existingunits, the ram is sometimes lowered again causing failure of the press,work and tools. It cannot occur with the anti-jump provision of thepresent invention.

The operation of the punch in this embodiment of the invention issubstantially the same .as previously described. In its descent, the ram45 of the press strikes the cap 73, moving the tubular member 71, punch5 0 and stripper member 30 downwardly. The stripper member 80 moves withthe punch and the tubular member 71, against the resistance of thespring 85. When the stripper member 80 engages the upper face of thework 56, its downward movement is arrested, but the downward movement ofthe ram continues to drive the punch through the work. In this continueddownward movement, the solid member 76 is compressed in volume, as shownby a comparison of Figs. 7 and 8, and the punch is driven through thework to perforate the work and punch a slug 51 therefrom. When the ramreverses its movement, returning upwardly, the com pressed solid member76 is free to expand to its former volume again, withdrawing the punchfrom the work. Then the spring 85 is free to return the punchassemblage, also, to its upper position, the parts assuming thepositions shown in Fig. 7.

As is evident, in the perforating units described the heavy coilstripping spring heretofore required in conventional perforating units,is eliminated. With the novel construction of the present inventioncloser hole centers can be punched; and sheets of given thickness can bepunched on smaller presses, or sheets of .greater thickness thanheretofore possible can be punched on conventional size presses. Inaddition because of the reduced mass of the punch assemblage, higherspeed presses can be used.

While the invention has been described in connection with severaldifferent embodiments thereof, it will be understood that it is capableof further modification, and this application is intended to cover anyvariations, uses, or adaptations of the invention following, in general,the principles of the invention and including such departures from thepresent disclosure as come within known or customary practice in the artto which the invention pertains, and as fall within the scope of theinvention or the limits of the appended claims.

Having thus described my invention, what I claim is:

l. A self-contained perforating unit comprising a C-frame, a die membercarried by one arm of said C-frame, a punch member mounted toreciprocate in the other arm of said .C-frame in .axial alignment withsaid die member and extending above and below said other arm, said punchmember being hollow .and having a shearing portion at its lower end, acompressible stripping means mounted in the hollow portion of .saidhollow punch member, a stripping member positioned between said twoarms, said punch member being reciprocable in said stripping member,said stripping member being normally positioned adjacent to and belowthe lower end of the shearing portion of said punch member, and meansconnecting said stripping member to said compressible stripping means tocompress said compressible stripping means on the punching stroke ofsaid punch member.

2. A self-contained perforating unit comprising a holder, a punch membermounted on said holder and having a shearing portion at its lower end,said punch member being hollow and closed at its upper end, acompressible solid material positioned in the hollow portion of saidpunch member, a sealing member sealing said solid material againstextrusion from the lower end of said punch member, a stripping member inwhich said punch member is reciprocable, said stripping member beingpositioned to engage the work on the perforating stroke of theperforating unit, a piston acting against said seal and means connectingsaid stripping member through said punch member to said piston tocompress said solid material after said stripping member has engaged thework, whereby on release of the punching force, said compressible solidmaterial will expand to strip the punch member from the work.

3. A combination punch and stripping assemblage comprising a punchmember having a bore closed at one end and having a shearing portion atone end, a compressible solid material positioned in the bore of saidpunch member, at least one sealing member sealing said solid materialagainst extrusion from said punch member, a piston member acting againstsaid sealing member, and a stripping member external of said punchmember and in which said punch member is slidable, said stripping memberbeing connected to said piston to compress said compressible materialupon relative movement between said stripping member and said punchmember on the punching stroke of said punch member, thereby to apply astripping force to said punch member upon completion of said punchingstroke, and adjustable means for preloading said compressible materialwhereby to vary the preload of said solid material for differentstripping conditions.

4. A self-contained perforating unit comprising a C-frame, a die membermounted on the lower arm of said C-frame, a punch member mounted toreciprocate in a bore formed in the upper arm of said C-frame in axialalignment with said die member, said punch member having a shearingportion at its lower end, a lifting spring interposed between saidC-frame and said punch member for elevating said punch member to providework feed clearance between said punch member and said die member, astripping member in which said punch member is slidable, said strippingmember having a lost motion connection with said punch member to limitthe upward, lifting movement of said punch member and to permit saidpunch member to efiect the perforating operation after said strippingmember has engaged the work on the perforating stroke of the perforatingunit, and a compressible stripping medium in said punch member, meansfor connecting said stripping member and said compressible strippingmedium to compress said compressible stripping medium upon relativemovement between said stripping member and said punch member on theperforating stroke of said perforating unit, whereby upon withdrawal ofthe punching force said stripping medium will expand to withdraw thepunch member from the work.

5. A perforating punch assemblage comprising a punch member having abore closed at one end, said punch member having a shearing portion atone end, a compressible solid material within said bore and adapted tosupport said punch member against deflection and to provide the forcefor stripping said punch member from the work after a perforatingstroke, and stripping means relative to which said punch member isslidable, said stripping means including a stripping member positionedto engage the work on the perforating stroke of said perforating unit,said stripping member being operatively connected with said compressiblematerial to compress said compressible material after said strippingmember has engaged the work and during the perforating operation of saidpunch member,

whereby upon release of the punching force, said compressible memberexpands to strip said punch member from the work.

6. A perforating punch assemblage comprising a punch member having abore closed at its upper end, said punch member having a shearingportion at its lower end, a compressible solid material in said boreadapted to support said punch against lateral deflection and to providethe stripping force, and a stripping memher in which said punch memberis slidable and normally positioned adjacent to and below the lower endof said punch member, said stripping member being operatively connectedto said compressible material to compress said compressible materialwhen said stripping member engages the work on the perforating stroke ofsaid punch assemblage, whereby to strip said punch member from the workupon completion of said stroke, said stripping member being tubular andsurrounding and supporting said punch member against outward deflection.

7. A combination punch and stripping assemblage comprising a cylindricalmember for transmitting the punching force and having a bore which isclosed at one end, a punch secured to the lower end of said cylindricalmember, a compressible solid material in said bore and adapted tostiffen said cylindrical member against lateral deflection but yieldableon compression to provide a resilient stripping force, and a strippingmember positioned to engage the work on a perforating stroke of saidpunch, said member having a lost-motion connection with said punch 'tomove therewith on the first part of said perforating stroke but topermit said punch to efiect the punching operation after said strippingmember has engaged the work, said stripping member being connected tosaid compressible solid material to compress said material during thepunching operation.

8. A combination punch and stripping assemblage comprising a punchsupporting member having a bore which is closed at one end, aninsertable punch bit mounted in the other end of said bore, acompressible solid material mounted in said bore between said punch bitand said one end of said punch supporting member, a stripping memberhaving a lost-motion connection with said punch supporting member andpositioned to engage the work on the perforating stroke of saidassemblage, and means connecting said stripping member to saidcompressible material to compress said material on a working stroke ofsaid punch, whereby said material will strip the workpiece from thepunch upon release of the punching load applied thereto.

9. A self-contained perforating unit comprising a holder, a strippermember, a tubular punch member which is closed at one end and which hasa shearing portion at its opposite end, said punch member beingreciprocable in said holder and in said stripper member, a compressiblematerial mounted in the bore of said punch member, and lost-motion meansconnecting said punch member to said stripper member so that the twomembers move together on a working stroke of the punch until thestripper member engages the work and so that thereafter on continuationof said working stroke said compressible material is compressed so thatwhen said punch member is relieved of the punching force, saidcompressible material will return the punch to initial position.

10. A self-contained perforating unit comprising a holder, a tubularpunch member-which is closed at its upper'end and which is reciprocablein said holder, an inserted punch bit secured in the lower end of saidpunch member, a compressible member mounted in the bore of said tubularmember between its upper end and said punch bit, a tubular strippermember surrounding said punch member and in which said punch member andsaid punch bit are reciprocable, said stripper member being normallypositioned adjacent to and below the lower end of said punch bit,lost-motion means operatively connecting said tubular punch member tosaid stripper member, and means operatively connecting said strippermember to said compressible member to compress said compressible memberupon relative motion between said punch member and said stripper memberon the punching stroke of said unit.

ll. A self-contained perforating unit comprising a holder, a tubularpunch member which is closed at its upper end and which is reciprocablein said holder, an inserted punch bit secured in the lower end of saidpunch member, a piston, a compressible member mounted in the bore ofsaid tubular member and interposed between said piston and the upper endof said tubular member, a stripper member in which said punch member isreciprocable, said stripper member being normally positioned adjacent toand below the lower end of said punch bit, a lost-motion connectionbetween said stripper member and said punch member, and meansoperatively connecting said piston to said stripper member to compresssaid compressible member on the punching stroke of said punch memberafter said stripper member has engaged the work.

12. A self-contained perforating unit comprising a holder having anupper arm and a lower arm, a die member mounted on said lower arm, atubular punch member which is closed at its upper end and which ismounted reciprocably in said upper arm in axial alignment with said diemember, a reciprocable stripper member mounted below said upper arm andthrough which said punch member reciprocates, a compressible membermounted in the bore of said tubular member, a punch bit inserted in thelower end of said bore, means connecting said compressible member withsaid stripper member to transmit motion from the punch member to thestripper member during part of a working stroke of the punch member andto compress said compressible member when said stripper member engagesthe work during a further part of said working stroke, whereby uponrelease of the punching force said compressible member will expand toreturn said punch member to initial position and strip said punch bitfrom the work, and means for returning said stripper member to initialposition, said stripper member being so disposed that said upper armacts as a stop limiting its return movement.

13. A self-contained perforating unit comprising a holder having anupper arm, and a lower arm, a die member mounted on said lower arm, atubular punch member which is closed at its upper end and which ismounted reciprocably in said upper arm in axial alignment with said diemember, a reciprocable stripper member mounted below said upper arm andthrough which said punch member reciprocates, a compressible solidmember mounted in the bore'of said tubular member, a punch bit insertedin the lower end of said bore, means connecting said compressible memberwith said stripper member to transmit motion from said punch member tosaid stripper member during part of a working stroke of the punch memberand to compress said compressible member when said strippermember'engages the work during a further part of saidworking stroke,whereby upon release of the punchingforce said compressible member willexpand to return said punch member to initial position and strip saidpunch bit from the work, and means for returning said strippermember' toinitial position, said stripper memberbeing' so disposed thatit engagessaid upper arm 13 on its return movement, whereby said upper arm acts asa stop limiting the return movement of said stripper member.

14. A self-contained perforating unit comprising a holder having anupper arm, and a lower arm, a die member mounted on said lower arm, atubular punch member mounted reciprocably in said upper arm in axialalignment with said die member, a reciprocable stripper member mountedbelow said upper arm and through which said punch member reciprocates, acompressible solid material mounted in the bore of said tubular member,a punch bit inserted in the lower end of said bore, means confining saidsolid material at its upper end, a seal confining said solid material atits lower end, a piston slidable in said bore and engaged by said seal,means extending through a slot in said punch member to operativelyconnect said stripper member with said piston so that said compressiblematerial is compressed upon relative movement between said strippermember and said punch member on the working stroke of said punch member,and spring means connecting said stripper member to said upper arm toconstantly urge said stripper member to return to its initial position,said stripper member being so disposed that it engages said upper arm onits return movement, whereby said upper arm acts as a stop limiting thereturn movement of said stripper member.

15. A self-contained perforating unit comprising a holder having anupper arm and a lower arm, a die member mounted on said lower arm, atubular punch member mounted reciprocably in said upper arm in axialalignment with said die member, a reciprocable stripper collar mountedbelow said upper arm and surrounding said punch member, a compressiblesolid material mounted in the bore of said tubular member, a punch bitinserted in the lower end of said bore, means confining saidcompressible material at its upper end, a seal confining saidcompressible material at its lower end, a piston slidable in said boreand engaged by said seal, a pin extending through an elongate slot insaid punch member and connecting said piston to said stripper member tocompress said compressible material upon relative movement between saidstripper member and said punch member on the working stroke of saidpunch member, and spring means disposed above said upper arm andabutting at one end against said upper arm and connected at its otherend to said punch member to return said stripper member to initialposition.

16. A self-contained perforating unit comprising a holder having anupper arm and a lower arm, a die member mounted on said lower arm, atubular punch member mounted reciprocably in said upper arm in axialalignment with said die member, a reciprocable C-shaped stripper membermounted below said upper arm and in which said punch member isreciprocable, a compressible solid material mounted in the bore of saidtubular member, a punch bit inserted in the lower end of said bore,means confining said compressible material at its upper end, a sealconfining said compressible material at its lower end, a piston slidablein said bore and engaged by said seal, said stripper member having itsupper arm extending through an elongate slot in said punch member, a pinconnecting the upper arm of said stripper member with said piston tocompress said compressible material upon relative movement between saidstripper member and said punch member on the working stroke of saidpunch member, and a spring connecting said stripper member with theupper arm of said holder to constantly urge said stripper member toreturn to its initial position, said stripper member being so disposedthat it engages said upper arm on its return movement, whereby saidupper arm acts as a stop limiting the return movement of said strippermember.

17. A self-contained perforating unit comprising a holder having anupper arm, and a lower arm, a die member mounted on said lower arm, atubular punch member mounted reciproca'bly in said upper arm in axialalignment with said die member, a reciprocable stripper member mountedbelow said upper arm and through which said punch member reciprocates, acompressible solid material mounted in the bore of said tubular member,a punch bit inserted in the lower end of said bore, means confining saidsolid material at its upper end, a seal confining said solid material atits lower end, a piston slidable in said bore and engaged by said seal,means extending through a slot in said punch member to operativelyconnect said stripper member with said piston to compress saidcompressible material upon relative movement between said strippermember and said punch member on the working stroke of said punch member,and spring means connecting said stripper member to said upper arm toconstantly urge said stripper member to return to its initial position,said stripper member being so disposed that it engages said upper arm Onits return movement, whereby said upper arm acts as a stop limiting thereturn movement of said stripper member, said confining means beingadjustable for preloading said solid material.

18. A self-contained perforating unit comprising a C-frame, a die membercarried by one arm of said C-frame, a punch member mounted toreciprocate in the other arm of said C-frame in axial alignment withsaid die member, said punch member being hollow and having a shearingportion at its lower end and being closed at its upper end, acompressible solid mounted in the hollow portion of said hollow punchmember, a stripper member positioned to engage the work and in whichsaid punch member is slidable, a lost-motion connection between saidstripper member and said punch member, and means connecting saidstripper member to said compressible solid for transmitting strippingforces between said compressible solid and said stripper member.

19. A self-contained perforating unit comprising a O-frame, a die membercarried by one arm of said C-frame, a punch member mounted toreciprocate in the other arm of said C-frame in axial alignment withsaid die member, said punch member being hollow and having a shearingportion at its lower end and being closed at its upper end, acompressible solid mounted in the hollow portion of said hollow punchmember, a stripper member positioned to engage the work and in whichsaid punch member is slidable, a lost-motion connection between saidstripper member and said punch member, and means connecting saidstripper member and said compressible solid for transmitting strippingforces between said compressible solid and said stripper member, andmeans for preloading said compressible solid.

20. A self-contained perforating unit comprising a 0- frame, a diemember carried by one arm of said Cframe, a punch member mounted toreciprocate in the other arm of said C-frame in axial alignment withsaid die member, said punch member being hollow, a compressible solidmaterial mounted in the hollow portion of said punch member and confinedtherein at both its upper and its lower ends, a punch bit inserted inthe lower end of said punch member, a stripper member positioned toengage the work and in which said punch member is slidable, alost-motion connection between said stripper member and said punchmember, and means connecting said stripper member to said compressiblematerial for transmitting stripping forces between said compressiblematerial and said stripper member.

21. A self-contained perforating unit comprising a C- trame, a diemember carried by one arm of said C-frame, a punch member mounted toreciprocate in the other arm of said C-frame in axial alignment withsaid die member, said punch member being hollow, a compressible solidmaterial mounted in the hollow portion of said punch member and confinedtherein at both its upper and its lower ends, a punch bit inserted inthe lower end of said punch member, a stripper member positioned toengage the work and in which said punch member is slidable, and meansconnecting said stripper member and said compressible material fortransmitting stripping forces between said compressible material andsaid stripper memher, and means for preloading said compressiblematerial.

22. A self-contained perforating unit comprising a C- t'rame, a diemember carried by one arm of said C-frame, a tubular punch membermounted to reciprocate in the other arm of said C-frame in axialalignment with said die member, said punch member being closed at itsupper end, a compressible solid mounted in the bore of said punch memberand confined at its upper end by the closed upper end of said tubularmember, means confining the lower end of said compressible solid, apunch bit insorted in the lower end of said punch member, a strippermember positioned to engage the work and in which said punch member isslidable, and means interposed between said punch bit and the last-namedmeans for operatively connecting said stripper member to saidcompressible solid to compress said compressible solid upon relativemovement between said stripper member and said punch member on theworking stroke of said perforating unit.

23. A self-contained perforating unit comprising a C-frame, a die membercarried by one arm of said C- frnme, a tubular punch member mounted toreciprocate in the other arm of said C-frame in axial alignment withsaid die member, said punch member being closed at its upper end, acompressible solid mounted in the bore of said punch member and confinedat its upper end by the closed upper end of said tubular member, meansconfining the lower end of said compressible solid, a punch bit insertedin the lower end of said punch member, a stripper member positioned toengage the work and in which said punch member is slidable, and meansextending through an elongate slot in said punch member and interposedbetween said punch bit and said last-named means for operativelyconnecting said stripper member to said compressible solid to compresssaid compressible solid upon relative movement between said strippermember and said punch member on the punching stroke of said perforatingunit.

24. A self-contained perforating unit comprising a frame, a die membercarried by one arm of said C- frame, a tubular punch member mounted toreciprocate in the other arm of said C-frame in axial alignment withsaid die member, a cap threaded on the upper end of said punch member toclose the upper end of its bore, a compressible solid mounted in thebore of said punch member and confined at its upper end by said cap, aseal confining said compressible solid at its lower end in said bore, apunch bit inserted in the lower end of said bore, a reciprocablestripper member positioned to engage the work and in which said punchmember is slidable, and means interposed between said seal and saidpunch bit for operatively connecting said stripper member to saidcompressible solid to compress said compressible solid upon relativemovement between said stripper member and said punch member on thepunching stroke of said perforating unit.

25. A self-contained perforating unit comprising a holder having upperand lower arms, a die member carried by one arm of said holder, atubular punch member mounted to reciprocate in the other arm of saidholder in axial alignment with said die member, said tubular memberbeing closed at its upper end and having a bore portion which is conicaland larger at its upper end than at its lower end, a compressibleconical solid member mounted in said bore portion, said bore having acylindrical portion joining the lower end of said conical portion, acylindrical piston reciprocable in the cylindrical 16 portion of saidbore, a punch bit secured to said tubular member below said piston, astripper member in which said tubular punch member and said punch bitare slidable, and means connecting said piston to said stripper memberto compress said compressible member upon relative movement between saidstripper and said punch member on the punching stroke of saidperforating unit.

26. A perforating punch assemblage of reduced mass comprising a tubularpunch body, a punch insert fastened in said tubular body at one endthereof, and stripping means mounted both within and without said punchbody, said punch body being reciprocable in the outside stripping meansand being connected to said outside stripping means by a lost-motionconnection, said outside stripping means being positioned to engage thework on a working stroke of said assemblage, and the inside strippingmeans being compressible and being connected to the outside strippingmeans to be compressed upon relative movement between said outsidestripping means and said punch body on the working stroke of saidassemblage.

27. A perforating punch assemblage comprising a support, a tubular punchbody reciprocable in said support, a pair of spaced plug members forclosing a portion of said tubular body at opposite ends thereof, atleast one of said plug members being slidable in said body, acompressible solid positioned between said plug members in said body, apunch insert secured in said punch body at one end thereof, andstripping means surrounding said body and in which said body isslidable, and a lostmotion connection connecting said stripping means tosaid punch body, said stripping means being operatively connected to oneof said plugs to compress said compressible solid upon relative movementbetween said stripping means and said punch body on the Working strokeof said punch body.

28. A perforating punch assemblage comprising a support, a tubular punchbody reciprocable in said support, a punch bit secured in one end of thebore of said body and having a locking tapered fit in said bore,compressible stripping means mounted in said body, a stripper positionedto engage the work and in which said body is slidabie, a lost-motionconnection between said stripper and said body, and means connectingsaid stripping means to said stripper to compress said stripping meanson relative motion between said stripper and said body on the workingstroke of said body.

29. A perforating punch assemblage comprising a support, a tubular punchbody reciprocable in said support, a hardened punch bit secured in thelower end of the bore of said body and'having a locking tapered fit insaid bore, a compressible solid mounted in said bore above said punchbit, means closing the upper end of said bore, a stripper positioned toengage the work and in which said body is slidable, a lost-motionconnection between said stripper and said body, and means connectingsaid compressible solid to said stripper to compress said compressiblesolid upon relative movement between said stripper and said punch bodyon the working stroke of said punch body.

References Cited in the file of this patent UNITED STATES PATENTS TaylorMar. 15, 1955

